Estrogen exposure is well-documented to be important in the pathogenesis of endometrial cancer. We hypothesize that normal growth control pathways induced by estrogen are dysregulated in endometrial hyperplasia and cancer. By identifying genes that are dysregulated, we can 1) further our understanding of the step-wise progression in endometrial carcinogenesis and 2) identify genes that can be used as surrogate biomarkers of endometrial cancer risk. Identification of these tissue biomarkers is crucial for the successful design of chemoprevention trials. In addition, these biomarkers potentially can be used clinically as tissue indicators of risk in high-risk groups. High risk groups include women using SERMs such as tamoxifen, women with HNPCC, and women with obesity and type 2 diabetes. We have recently analyzed gene expression changes in post-menopausal endometrium exposed to different estrogen preparations using DNA microchip army analysis and real-time quantitative PCR (Q-PCR). The array analysis identified several hundred genes that are regulated by estrogen. From this large set of estrogen regulated genes, and additional genes selected for their role in the development of endometrial hyperplasia, a set of 33 transcripts was identified that are involved in proliferation in the endometrium. Our approach will be to make quantitative measurements of mRNA levels of this set of potential biomarkers in endometrial biopsy samples in different states of proliferation: normal, hyperplasia, and cancer. Specifc Aim 1: Quantitate the set of 33 candidate biomarkers in normal quiescent post-menopausal endometrium; normal proliferative post-menopausal endometrium from women treated with conjugated estrogens; normal secretory and normal proliferative pre-menopausal endometrium; hyperplastie endometrium both with and without nearby cancer; Type I endometrial cancer; and Type II endometrial cancer. Using laser capture microdissection, we will focus on the precancerous lesion endometrial intraepithelial neoplasia (EIN) and assess transcript levels in EIN and in normal adjacent regions. Specific Aim 2: High density microarrays will be screened to identify new genes whose expression is altered in hyperplasia and cancer compared to normal endometrium. Genes that are identified by the microchip analysis will be validated by Q-PCR. The combination of Aims 1 and 2 will identify a set of "abnormal proliferation" biomarker transcripts. Specific Aim 3: We will test the ability of the biomarkers to predict changes in proliferation by quantitating transcript levels in women treated with progestins for atypical hyperplasia. We hypothesize that biomarkers that are elevated in abnormal proliferation will be reduced by progestin treatment. Biomarkers will also be quantitated in endometrial biopsies from women treated with tamoxifen, a group at risk for developing endometrial cancer. This panel of biomarkers may be extended for use in the future analysis of the endometrial effects of newer SERMs.